1. School of Computer Science, Carnegie Mellon University, United States. yohanj@andrew.cmu.edu
2. School of Computer Science, Carnegie Mellon University, United States. seojinb@andrew.cmu.edu
3. Centre for Argument Technology, University of Dundee, United Kingdom. ehovy@andrew.cmu.edu
4. School of Computer Science, Carnegie Mellon University, United States. c.a.reed@dundee.ac.kr